JPH11166171A - Composite solid particle and production thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To carry out the compositing or surface modicication of solid particles and enable the content of fine particles to be freely adjusted by fixing fine particles (child particles) to the surfaces of core particles (mother particles) and causing the crystals of the fixed fine particles to grow. SOLUTION: Cellulose or its deriv., starch or its deriv., a synthetic polymer (e.g. nylon), a metal powder (e.g. a nickel or iron powder), or an inorg. powder (e.g. an alumina powder) is used as the mother particles; and an inorg. or org. compd. having crystallizing properties, as child particles. The child particles are fixed to the surfaces of the mother particles by a mechanical method, such as an impact method in a high-speed air flow. When calcium monohydrogenphosphate (CaHPO4 ), having a very low water solubility, is used as the child particles, the crystal growth of fixed child particles is conducted by a solid-liquid reaction method in the supersatd. state. For instance, a calcium hydroxide suspension is reacted with pyrophosphoric acid in an aq. soln. adjusted to a pH of 4.5-5.8, pref. 5.7, thus forming CaHPO4 and causing the crystals of CaHPO4 to grow while using CaHPO4 fixed on the mother particles as crystallization nuclei.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention belongs to the technical field of surface-modified composite solid particles and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, fine particles (hereinafter, referred to as "child particles") are fixed to the surface of core particles (hereinafter, referred to as "base particles") to prevent caking, prevent discoloration and alteration, improve dispersibility,
A method for producing composite solid particles for the purpose of improving the catalytic effect, improving the magnetic properties, and the like is known, for example, from Japanese Patent Publication No. 3-2009. By adopting the high-speed air-flow impact method, which is a dry particle compounding method that does not require an organic solvent or water as described here, a functional composite / hybrid powder having uniform and stable characteristics Materials (composite or hybrid powder) can be produced efficiently.

[0003]

However, in the composite solid particles produced by the above method, the child particles only have the child particles fixed uniformly on the surface of the base particles, so that the child particles have an effect on the improvement of the functionality. Is approximately determined by the surface area of the mother particles and the cross-sectional area (projected area) of the child particles. In general, the maximum weight ratio of the child particles to the mother particles is considered to be a ratio of the child particles covering almost one layer of the surface of the mother particles. Then, the maximum weight ratio of the child particles to the mother particles becomes the maximum weight ratio. = (4rρ1 / Rρ0) × 100% where r: child particle radius ρ1: child particle density R: base particle radius ρ0: base particle density As a result, when the radius and the density of the mother particle and the child particle are determined, the maximum weight ratio of the child particle is determined, and the weight ratio cannot exceed this.
There is a problem that further improvement in function cannot be expected, and there is a problem to be solved by the present invention.

[0004]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and has been made for the purpose of solving these problems. The first invention is directed to the surface of core particles. In producing the composite solid particles by immobilizing the fine particles, the production of the composite solid particles by fixing the fine particles on the surface of the core particles and then growing the crystal of the fine particle component on the fine particle-fixed particles Is the way. Further, the second invention, in modifying the surface of the solid particles by immobilizing the fine particles on the surface of the core particles to form a composite solid particles, the fine particles are fixed to the surface of the core particles The composite solid particles are obtained by growing crystals of the fine particle component on the fixed fine particles. In this method, the crystal growth of the fine particle component is obtained by mixing fine particle-fixed particles in a fine particle component solution and growing the crystal with the fixed fine particles as crystal nuclei. The fine particle component solution is obtained by reacting and generating a fine particle component in a liquid phase. In this, the fine particle component is calcium monohydrogen phosphate. In this case, the crystal growth of the fine particle component is performed when the hydrogen ion index (pH value) is 4 to 6, preferably 4.5 to 6.
During 5.8, more preferably with an aqueous solution adjusted to 5.7. Here, the calcium monohydrogen phosphate is formed by adding pyrophosphoric acid to a suspension of calcium hydroxide and causing the reaction to proceed.

[0005] In the crystal obtained by performing the method of the present invention, the content of the child particles can be adjusted according to the degree of the crystal growth, and the child particles cannot be formed by the conventional fixing method. Control to freely increase the content ratio can be performed. When the growing crystal has a long growth like a needle or a column, the surface area of the child particles can be significantly increased. In addition, composite solid particles in which needle-like or columnar crystals, which could not be obtained by the conventional fixing method, are joined to the base particles at one end in the longitudinal direction can be obtained.

[0006] As a result, the composite solid particles obtained by crystal growth of the child particle component greatly improve various functions (eg, electronic and magnetic characteristics, optical characteristics, thermal characteristics, biological characteristics, etc.) of the child particles. In addition to the improvement, the compression moldability, the content uniformity property and the like can be improved. In addition, various reaction rates can be improved by increasing the surface area of the child particles. And composite solid particles are electric / electronic materials, magnetic materials, optically functional materials, pharmaceuticals, cosmetics, biomaterials,
It can be used for building materials.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The base particles used for producing the composite solid particles of the present invention include, for example, various celluloses such as crystalline cellulose, hydroxypropyl cellulose, carboxymethyl cellulose and derivatives thereof, potato starch, corn starch, wheat starch. , Partially soluble starch, starches such as dextrin and derivatives thereof,
It is a saccharide such as lactose and a synthetic polymer such as nylon, polyethylene and polystyrene. In addition, metal powders such as iron, nickel, aluminum and copper, and inorganic substances such as alumina, zirconium and silicon carbide can also be used as the base particles. The child particles are materials having crystal growth characteristics, such as various crystalline inorganic compounds and organic compounds. Examples of the crystalline inorganic compound include hydroxides, halides, carbonates, sulfates, nitrates, phosphates, hydrogen phosphates, and silicates of various metals. As crystalline organic compounds, ibuprofen,
It is a crystalline drug such as ketoprofen, flurbiprofen, indomethacin, phenacetin, oxyphenbutazone, etenzazamide, saltylamide, salicylic acid, benzoic acid and the like. When it is desired to obtain a composite particle in which a crystal of a metal oxide having extremely low solubility in water is grown on the surface of the base particle, a metal hydroxide, a halide, a carbonate, a sulfate, a nitrate, a phosphate, or the like may be used. , And then calcined after crystal growth as hydrogen phosphate or the like.

[0008] As a method for fixing the child particles to the base particles, a generally known method can be adopted, and specifically, the above-mentioned Japanese Patent Publication No. 3-2009 and Japanese Patent Laid-Open No. 6-2 / 1994.
Various mechanical fixing methods are exemplified by the high-speed airflow impact method described in Japanese Patent No. 10152, but are not limited thereto as long as the child particles can be fixed to the base particles. The size of the mother particles is suitably in the range of 0.5 μm (micrometer) to 2 mm. When the high-speed airflow impact method is used as a method of fixing the child particles to the base particles, if the size of the base particles is less than 0.5 μm, the base particles float in the airflow, and the applied impact force is not easily transmitted to the particles. On the other hand, if it exceeds 2 mm, the particles are likely to be broken by impact, and it is difficult to obtain particles of a predetermined quality, which is not efficient. The shape of the base particles is preferably spherical or elliptical, but may be any other unspecified shape. In the case of various mechanical methods (immobilization method), the size of the child particles is one of the size of the mother particles.
/ 5 or less, more preferably 1/10 or less, and specifically, the particle size is 0.01 to 1
It is about 0 μm. In the case of using the high-speed air-flow impact method, the crystalline particles are selectively pulverized in an impact chamber of a powder surface modification treatment apparatus described later, so that the size of the child particles (the substance to be fixed) is reduced. It does not matter in particular. Further, as a method of crystal growth, there are a physical growth method such as vacuum evaporation, a growth method of growing in a gas phase or a liquid phase, and further a growth method in a solid phase, and any of these methods can be used. .
For example, the liquid phase growth method is a method of growing crystals from a solution in which a child particle material (solute) is dissolved in a solvent in a supersaturated state. Supersaturated solutions can be obtained by cooling the solution,
It can be obtained by a method of evaporating the solvent, a method of pressurizing the solution, a solid-liquid, solution, gas-liquid reaction, or the like.

The particles are composed of calcium monohydrogen phosphate (CaHP).
O4), this material has very low solubility in water (0.02 g / 100 g, at 24.5 ° C.)
Therefore, the crystal growth is performed in a supersaturated state obtained by a reaction method (solid-liquid reaction method). For example, while reacting calcium hydroxide suspension with pyrophosphoric acid to generate calcium monohydrogen phosphate, It is preferable to grow calcium monohydrogen phosphate immobilized as a crystal nucleus. The reaction solution in this case has a hydrogen ion index (pH value) of 4 to 6,
It is preferably in the range of 4.5 to 5.8, and more preferably adjusted to 5.7.

<Experimental Example> Next, an experimental example will be described. An experiment was conducted in the case where nylon 12 was used as the base particles and calcium monohydrogen phosphate was used as the child particles. Formation of Fine Particle-Adhered Particles Spherical particles of nylon 12 having a mean particle diameter of 50 μm (manufactured by Toray Industries, Inc.) having a mean particle diameter of 50 μm, and a plate-like phosphoric acid having an average length of one side of about 50 μm as a child particle. A mixed powder of 10: 1 in weight ratio with calcium hydrogen (special grade, manufactured by Wako Pure Chemical Industries, Ltd.) was applied to a powder surface reforming apparatus (NH
The above-mentioned powder surface modification treatment is carried out using an SO type (manufactured by Nara Machinery Co., Ltd.) under the following conditions (a treatment according to the method described in Japanese Patent Publication No. 3-2009). Calcium hydrogen phosphate selectively pulverized in the impact chamber of the device was embedded and fixed in the form of fine particles on the surface of the nylon 12 spherical particles, thereby obtaining fine particle-fixed particles having calcium hydrogen phosphate fixed to the surface. FIG. 1 shows a scanning electron micrograph of the fine particle-fixed particles as a drawing substitute photograph. Charge: 10 g Rotation speed: 12000 rpm Processing time: 5 minutes Preparation of calcium hydrogen phosphate production solution 0.7409 g of fine-particle calcium hydroxide (special grade, manufactured by Kanto Chemical Co., Ltd.) is charged with 100 g of purified water. Into a container to prepare a suspension of calcium hydroxide, and 100 g of an aqueous solution of pyrophosphoric acid (primary grade, manufactured by Showa Chemical Co., Ltd.) having a concentration of 0.05 mol / l was added to the suspension for 10 minutes while stirring. Add slowly. Next, a magnetic stirrer (RC-10, manufactured by Tokyo Rigaku Machine Co., Ltd.)
After stirring for 2 hours using, the reaction solution is filtered (to filter large crystals and impurities formed in the initial stage of the reaction) to obtain a solution of calcium hydrogen phosphate as a filtrate. This product was suspended. This product solution is adjusted to pH
The value is adjusted using purified water and the aqueous solution of pyrophosphoric acid so that the value becomes 5.70. Production of crystal growth particles 50 g of the above-prepared solution of calcium hydrogen hydrogen phosphate prepared above was placed in a glass container containing 100 mg of the fine particle fixed particles treated as described above, and the mixture was shaken by hand and mixed well. And let it stand at 25 ° C. Seven days later, composite solid particles in which crystals grew acicularly using calcium monohydrogen phosphate embedded in the surface of the nylon spherical particles as crystal nuclei were obtained. The solution was filtered, and the obtained filtrate was washed with water,
By drying, composite solid particles in which the child particle components grew were obtained. FIG. 2 shows a scanning electron micrograph of these particles as a drawing substitute photograph. It was confirmed that the crystal growth particles obtained here did not peel off the crystal from the base particle even if a slight impact was applied, and that the crystal was grown in a fixed state.

<Comparative Example 1> The weight ratio of the nylon 12 spherical particles used in the above experimental example to calcium monohydrogen phosphate was 10:
All of the mixed powder No. 1 was subjected to the same treatment as that of the above-mentioned experimental example except that the immobilization treatment using the powder surface modification treatment device was not performed, and a crystal growth was attempted. FIG. 3 shows a scanning electron micrograph of the resulting product as a drawing substitute photograph.
At first glance, it was observed that crystals grew on the base particles, but it was confirmed that the crystals were easily separated.

<Comparative Example 2> The product solution prepared as described above was treated in the same manner as in the experimental example except that the pH value was adjusted to 6.3. In this case, no crystal growth was observed. . FIG. 4 shows a scanning electron micrograph of the obtained particles as a drawing substitute photograph.

[Brief description of the drawings]

FIG. 1 is a photograph substituted for a drawing of a sample obtained by fixing calcium monohydrogen phosphate on the surface of nylon 12 spherical particles serving as base particles, which is taken by a scanning electron microscope.

FIG. 2 is a drawing substitute photograph of a particle obtained by growing a crystal in an experimental example, which is taken by a scanning electron microscope.

FIG. 3 is a drawing substitute photograph of the particles obtained in Comparative Example 1 taken by a scanning electron microscope.

FIG. 4 is a drawing substitute photograph of the particles obtained in Comparative Example 2 taken with a scanning electron microscope.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI C09C 3/06 C09C 3/06 C30B 29/62 C30B 29/62 Z

Claims (7)

[Claims] In producing composite solid particles by immobilizing fine particles on the surface of a core particle, the fine particles are fixed on the surface of the core particle, and then the fine particle component is added to the fine particle fixed particles. A method for producing composite solid particles obtained by growing crystals. 2. The method of fixing fine particles on the surface of a core particle to modify the surface of the solid particle into a composite solid particle, wherein the fine particle is fixed on the surface of the core particle. Composite solid particles obtained by growing crystals of a fine particle component on the particles. 3. The surface-modified solid according to claim 1, wherein the fine particle component is grown by mixing fine particle fixed particles in a fine particle component solution and growing the crystal with the fixed fine particles as crystal nuclei. Surface modification method for particles and solid particles. 4. The method according to claim 3, wherein the fine particle component solution is
Composite solid particles produced by reacting fine particle components in a liquid phase and a method for producing the same. 5. The composite solid particle according to claim 4, wherein the fine particle component is calcium monohydrogen phosphate, and a method for producing the same. 6. The method according to claim 5, wherein the crystal growth of the fine particle component is carried out with an aqueous solution whose hydrogen ion exponent is adjusted to 4.5 to 5.8, more preferably 5.7. Composite solid particles and method for producing the same. 7. The surface-modified composite solid particles according to claim 5 or 6, wherein the calcium monohydrogen phosphate is formed by adding pyrophosphoric acid to a suspension of calcium hydroxide and reacting the suspension. Production method.